/*
 * @(#)Headers.java	1.4 07/01/02
 *
 * Copyright 2007 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package com.sun.net.httpserver;

import java.util.*;
import java.io.*;

/**
 * HTTP request and response headers are represented by this class which implements
 * the interface {@link java.util.Map}&lt;
 * {@link java.lang.String},{@link java.util.List}&lt;{@link java.lang.String}&gt;&gt;.
 * The keys are case-insensitive Strings representing the header names and
 * the value associated with each key is a {@link List}&lt;{@link String}&gt; with one
 * element for each occurence of the header name in the request or response.
 * <p>
 * For example, if a response header instance contains one key "HeaderName" with two values "value1 and value2"
 * then this object is output as two header lines:
 * <blockquote><pre>
 * HeaderName: value1
 * HeaderName: value2
 * </blockquote></pre>
 * <p>
 * All the normal {@link java.util.Map} methods are provided, but the following 
 * additional convenience methods are most likely to be used:
 * <ul>
 * <li>{@link #getFirst(String)} returns a single valued header or the first value of
 * a multi-valued header.</li>
 * <li>{@link #add(String,String)} adds the given header value to the list for the given key</li>
 * <li>{@link #set(String,String)} sets the given header field to the single value given
 * overwriting any existing values in the value list.
 * </ul><p>
 * All methods in this class accept <code>null</code> values for keys and values. However, null 
 * keys will never will be present in HTTP request headers, and will not be output/sent in response headers.
 * Null values can be represented as either a null entry for the key (i.e. the list is null) or
 * where the key has a list, but one (or more) of the list's values is null. Null values are output
 * as a header line containing the key but no associated value.
 * @since 1.6
 */
public class Headers implements Map<String,List<String>> {

	HashMap<String,List<String>> map;

	public Headers () {map = new HashMap<String,List<String>>(32);}

	/* Normalize the key by converting to following form.
 	 * First char upper case, rest lower case.
	 * key is presumed to be ASCII 
 	 */
	private String normalize (String key) {
	    if (key == null) {
		return null;
	    }
	    int len = key.length();
	    if (len == 0) {
		return key;
	    }
	    char[] b = new char [len];
	    String s = null;
	    	b = key.toCharArray();
	        if (b[0] >= 'a' && b[0] <= 'z') {
		    b[0] = (char)(b[0] - ('a' - 'A'));
	        }
	        for (int i=1; i<len; i++) {
	            if (b[i] >= 'A' && b[i] <= 'Z') {
		        b[i] = (char) (b[i] + ('a' - 'A'));
	            }
	        }
	        s = new String (b);
	    return s;
	}

    	public int size() {return map.size();}

    	public boolean isEmpty() {return map.isEmpty();}

    	public boolean containsKey(Object key) {
	    if (key == null) {
		return false;
	    }
	    if (!(key instanceof String)) {
		return false;
	    }
	    return map.containsKey (normalize((String)key));
	}

    	public boolean containsValue(Object value) {
	    return map.containsValue(value);
 	}

    	public List<String> get(Object key) {
	    return map.get(normalize((String)key));
	}

	/**
	 * returns the first value from the List of String values
 	 * for the given key (if at least one exists).
	 * @param key the key to search for
	 * @return the first string value associated with the key
	 */
    	public String getFirst (String key) {
	    List<String> l = map.get(normalize((String)key));
	    if (l == null) {
		return null;
	    }
	    return l.get(0);
	}

    	public List<String> put(String key, List<String> value) {
	    return map.put (normalize(key), value);
	}

        /**
         * adds the given value to the list of headers
         * for the given key. If the mapping does not
         * already exist, then it is created
         * @param key the header name
         * @param value the header value to add to the header
         */
    	public void add (String key, String value) {
	    String k = normalize(key);
	    List<String> l = map.get(k);
	    if (l == null) {
		l = new LinkedList<String>();
		map.put(k,l);
	    }
	    l.add (value);
	}

        /**
         * sets the given value as the sole header value
         * for the given key. If the mapping does not
         * already exist, then it is created
         * @param key the header name
         * @param value the header value to set.
         */
    	public void set (String key, String value) {
	    LinkedList<String> l = new LinkedList<String>();
	    l.add (value);
	    put (key, l);
	}


    	public List<String> remove(Object key) {
	    return map.remove(normalize((String)key));
	}

    	public void putAll(Map<? extends String,? extends List<String>> t)  {
	    map.putAll (t);
	}

    	public void clear() {map.clear();}
    
    	public Set<String> keySet() {return map.keySet();}

    	public Collection<List<String>> values() {return map.values();}

    	public Set<Map.Entry<String, List<String>>> entrySet() {
	    return map.entrySet();
	}

    	public boolean equals(Object o) {return map.equals(o);}

    	public int hashCode() {return map.hashCode();}
    }
